I built a bolting (sifting) reel for the micro-mill, using old time mills like the one in Richfield as a pattern. Although old sources recommend bolting reels that are 12, 16, or 20' long, I am hoping that I can get away with a much shorter reel since I do not sift very finely. This reel is 12" in diameter and 24" long. The mesh is 32 mesh T316 stainless steel bolting cloth, which has openings of 629 microns.
Here is the reel, 6 sided and built on a 1 1/8" dowel.
Here is the cabinet going together. Angles are all 45 degrees, which works OK but I later found the flour can still hang up on the sides.
My Dad gave me a worm drive gearbox which had a 60:1 reduction. This works great although the cabinet is resonating and the 1/4 hp motor is making a lot of noise. The reel is turning about 45 rpm I'd say. The bearings are all hardwood, lubricated with beeswax at this point. I made the pulley on a lathe, quick and dirty.
Here is the bolting cabinet being tested with the mill. Flour comes out of the mill and gets dumped inside the reel while it turns. Flour comes out the small hole and bran the larger hole at left. The extraction level is 90%, based on the first full bag I milled. I am going to experiment with re-grinding the bran and increasing the extraction level. This mill spits out cracked grains and it really needs to have the bolting attachment at this point.
This 90% flour is really making a nice loaf. Here is my second attempt, which was the lightest and chewiest loaf I have made so far: